 as it sounds like Margaret's are. What I've done in the past for that, especially if they're fiberglass, because you can't really put a lot of pressure against them because they'll stretch, and then they kind of sag, and you don't want that. We would just take a piece of plywood, 3-8, something lightweight, and we would screw through it and put a couple of 2x4 handles on the back, and one guy would hold it against the screen, and the other guy would scrub.